In one of my applications where I used slipring motor and there is no provision for mechanical brakes, so plugging is used for braking. Now my question is, if there is power failure or one of the direction contactor (power) gets stuck up, how can the motor be stopped? As in both cases the equipment keeps on running due to inertia for some time.

 

Responding to Anonymous' query... You have two distinct and separate situations:

A) Fusing of Directional Contactor.
If there is a probability of such an event, then you must consider contactors having different materials to preclude, or at least ameliorate the conditions causing contact-fusing. Or you could investigate other systems: install an upstream device, i.e., a line contactor: a DC operated circuit breaker: or one equipped with capacitor-tripping.

B) Braking Systems.
Search the List archives for "Motor Braking", Fast Stopping" as well as their derivatives.

Regards,
Phil Corso, PE
Boca Raton, FL
[[email protected]] ([email protected]) {[email protected]}